Balance staff assembly for watches



Nov. 18, 1941. w. L. BRENDLER 2,263,484

BALANCE STAFF ASSEMBLY FOR WATCHES Filed Aug. v, 1941 20 TL3.J 25- Z? "15 7 x 7 7J5 J6 J5 %;m

" collet, and the roller table Patented Nov. 18, 1941 UNI TE?!) FPATEN T 0 FFl CE 2,263,484 BALANCE STAFF ASSEMBLY FOR WATCHES William L. Brendler, Mankato, Minn. .ApplicationlAugus't 7, 1941; Serial No. 405,847 I 7 Glaims.

The invention relates generallyto the art of watchr-ma-king and primarily seeks to provide a novel form of balance staff which will enable replacement of broken staff pivots with-great facility a-nd without any-danger of rendering untrue the assembly relation of the balance wheel, the hairspring, the hairspring collet, the roller table and the new pivots, or of damagingsany of these parts.

:It is well known to 'Watchmakers =-that.it is now-customary to form the -staif pivots which are received in the --jewel bearings directly on the ends of the balance staff. The balance wheel, the hairspring, the lhairspring collet, and the roller aresecured in rigid assembly relation on the staff, usually by staking. .It, therefore, becomes necessary, whenever a staif pivot is broken-and must bereplaced, to remove the hairspring and its supporting collet, the balance -wheel-and the roller table inorder to remount them on .a new balance-staff which :will provide the necessaryv new pivots. In the removal and remountin'g of these partsit isquite common to damage one or more thereof and it is extremely difficult, and-t0 a watchmaker of inferior ability almost impossible, to reassemble the parts in absolutely a true relation. It is obvious, therefore, that with the present equipment its ispossible to repair a-fine watch in which :a balance staff has been broken only at considerable expense *and time loss if the tim-e-keepingefliciency .of the watch is 'to be'maintained. It.is, therefore, an object of the present invention to provide a balance staff structure in which the pivots can be .replaced without the necessity of removing .and .reassembling the individual parts origi- .nally .mountedin .rigid assembly onzthe balance staif.

Another-object of the invention is-to provide an improved balance staff structure upon which the balance wheel, .the' hairspring, the hairspring .are mounted in rigid assembly,,said staff including a tapered-central bore and a tapered sliding staff equipped at-its .en'ds withpivots and removably mounted in and projectingat its ends from said .bore.

Another object of the invention is toprovide a balance staff structure of the nature stated which includes a. removable sliding staff having pivots formed on the ends thereof and a bead thereon'fordefinitely placing the pivo'ts in proper position in the staff, said sliding staff also having a recess therein in which a retaining annulus 'or detent formed on 'the staff readily engages for the purpose of frictionally maintaining the .assemblytof the balance staif .and the sliding. stalf.

Another object -.oi the .invention is .to provide in a watch structure a storage place in which a replacement sliding staff can be removably retainedso as tobe .readilyaccessible toa'watchsliding ..staif removed.

.Figure 3 is anenlargeddetail View illustrating the sliding staif per se.

Figure .4 is a detailrperspective viewof a watch .bndge equipped with astorage groove so as to actasa receptacle for a spare sliding staff.

In the example of embodiment of theinvention herein illustrated, the balance staff is constructed to include a tapered plug portion 5 from whicha reduced diameter balance wheel mounting hub-portion 6 .is upwardly extended. An additionally reduced hairspring collet mounting hub. portion 1 extends upwardly from the hub portion 5 and terminates in an upwardly tapered .end .8.

Beneath the plug portion.5 the balance staff includes a downwardly extending and tapered shank portion 9, and the vwhole balance staif comprising the portions 9, 5, 6 and 1 is provided with an axial bore in which is slightly tapered in the upward direction as viewed in Figures 1 and 2.

A roller table II is ,rigidly secured upon the balance staif shank portion 9 as by staking as indicated at I 2. The balance wheel generally designated I3 has its hub or central portion l4 rigidly secured 'upon the staif hub portion 6 as by staking as indicated at l5, and the hairspring assembly generally designated 5 has its center or supporting collet l 'l rigidly secured upon the staff portion 1 as by staking or burnished Iferred to become broken or in some manner displaced from their perfect, true assembly relation.

The balance staff bore If! is dimensioned to removably and snugly receive the tapered sliding staff l9 which is equipped at each end with the customary reduced pivot 20 designed to be received in a jewel bearing. At its lower end, and above the respective pivot 20, the sliding staff is equipped with an enlargement or bead 21 which abuts the lower end terminus of the roller table II and shank 9 to definitely place the sliding staff in the balance staff. The definite placement of this sliding staff is additionally secured by the provision of a recess or depression 22 at the upper end of the sliding staff, said recess being adapted to receive and be frictioned by the inwardly spun and longitudinally slitted end terminus or sleeve portion 23 of the tapered hub extension 8 of the balance staff. The inwardly spun portion 23 of the hub readily grips the sliding staff and retains it in place in the balance staff, but it is to be understood that the sliding staff may be readily removed from the bore ID by a suitable downward pull thereon without in anywise disturbing or straining the perfectly true assembled relation of the hairspring, the balance wheel and the roller table.

In Figure 4 of the drawing there is illustrated a bridge 24 which is removed from its normal position in the watch case. The under surface of the bridge, or in fact any other suitable stationary part within the watch case can be equipped with a longitudinal groove 25 into which a spare or replacement sliding staff 19 can be removably placed, the groove being upset, as at 26, to removably retain said sliding staff. In this manner replacement of the improved form of sliding staff herein disclosed can always be assured, and in cases where a jeweler is not equipped with the particular form of sliding staff replacement, the owner of the watch needing replacement of a pivot need not be frustrated in his attempt at proper replacement or delayed in such replacement by the necessity of communication with the factory.

The advantages of the particular removable sliding staff structure and balance staff assembly herein disclosed over the one-piece balance staff structures now customarily employed in watches should be obvious. Under present known practices, when it becomes necessary to replace a broken pivot, it is, of course, necessary to re-' place the whole balance staff. This means that the hairspring assembly, the roller table and the balance wheel must be individually removed from the balance staff. In accomplishing this removal of parts, it is quite common to so badly damage the balance wheel by denting or bending the same out of true that it is practically impossible to perfectly true the same in the reassembly which must follow. It is possible also to damage the roller table during the removal thereof from the staff, and when removing the hairspring assembly by application of a suitable tool and a squealing effort beneath the assembly collet, it very often happens that the hairspring is bent out of true. When this is done it means hours of work in an attempt to perfectly true the spring, and it is sometimes impossible to their original perfectly true condition. It will be obvious also that these tiny parts may become misplaced or lost during removal thereof.

After the parts above-mentioned have been removed from the broken balance staff, the watchmaker must look around for another staff to restore the parts which will form a proper replacement for the broken unit. Perfect replacement units are not always available at the time the particular repair is demanded and delays are sometimes caused by the necessity of communication with the factory for proper replacements, and in some cases watches have been rendered inefficient by installation of improper replacements in an effort to avoid such delays.

After the proper balance staff replacements have been procured by the watchmaker, the roller table is properly mounted thereon. It then becomes necessary to remount, true and repoise the balance wheel. The hairspring assembly is then remounted and it becomes necessary to true the balance wheel and the hairspring assembly. The whole balance staff assembly is now ready for replacement in the watch but this reassembly has been accomplished only after a considerable expenditure of time and labor, possibly several hours, and unless accomplished by a highly efficient watchmaker, it is quite likely that the timekeeping efficiency of the watch will be somewhat impaired. The structure herein disclosed isdesigned for and is capable of avoiding all of the objections to the previous practices hereinabcve noted.

In replacing broken pivots in the novel balance staff assembly structure herein disclosed and embodying the present invention, it is only necessary to apply nippers between the sliding staff bead 2i and the opposing surfaces of the staff shank 9 and roller table II to withdraw the sliding staff from its friction relation in the bore If] at 22, 23. By now turning over the bridge 24 of the watch, the watchmaker can free the sliding staff by removal of the upsets 26 and the desired replacement sliding staff is immediately available. This sliding staff can be slipped through the bore into the position illustrated in Figure 1 without removing or disturbing the previous perfectly true relation of the roller table II, the balance wheel l3, and the hairspring as sembly IS on the balance staff. By reason of the provision of this simple equipment, it is possible to effect a saving of approximately in time, labor and cost to the factory, the jobber, and the watch owner.

I am aware that attempts have been made heretofore to provide removable sliding staff structures, and I am aware also that although such structures have been known for many years they have never been found practical and the practices involving the replacement of broken balance staff pivots have remained unchanged up to the present time. By the improved equipment herein disclosed, however, the'necessary formation of the various parts of the balance staff assembly of individual parts and different materials is in nowise hampered and the particular formation of the tapered sliding staff I9 including the position retaining bead 2|, recess 22 and friction detent 23 provides a structure which will avoid all of the objections of the present practice and objectional prior art disclosures and provide a wholly practical balance staff assembly structure.

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of my invention.

1 claim:

1. A balance staff assembly for watches comprising a balance staff element; unitary balance wheel, roller table and hair-spring assembly structures secured rigidly but removably in true assembly relation on said staff element; said balance staff element having an axial bore therethrough, a sliding staff element removably mounted in said bore having a length for extending at each end beyond said balance staff and having a pivot formed on each extended end, and means engaging and frictionally retaining said sliding staff element in said bore, said last named means comprising a detent carried by one said element and a detent receiving recess carried by the other of said elements.

2. A balance staff assembly for watches comprising, a balance staff; unitary balance wheel, roller table and hairspring assembly structures secured rigidly but removably in true assembly relation on said staff; said balance staff having an axial bore therethrough, a sliding staff removably mounted in said bore having a length for extending at each end beyond said balance staff and having a pivot formed on each extended end, and means engaging and frictionally retaining said sliding staff in said bore, said frictional engaging means comprising a recess formed in said sliding staff and an indentation formed on said balance staff and engageable in said recess.

3. A balance staff assembly for watches comprising, a balance staff; unitary balance wheel, roller table and hairspring assembly structures secured rigidly but removably in true assembly relation on said staff; said balance staff having an axial bore therethrough, a sliding staff removably mounted in said bore having a length for extending at each end beyond said balance staff and having a pivot formed on each extended end, and means engaging and frictionally retaining said sliding staff in said bore, said frictional engaging means comprising an annular recess formed in said sliding staff adjacent one pivot thereof and an inwardly spun annulus formed on the adjacent end of the balance staff and engageable in said recess.

4. A balance staff assembly for watches comprising, a balance staff; unitary balance wheel, roller table and hairspring assembly structures secured rigidly but removably in true assembly relation on said staff; said balance staff having an axial bore therethrough, a sliding staff removably mounted in said bore having a length for extending at each end beyond said balance staff and having a pivot formed on each extended end.

said sliding staff being tapered and said bore being similarly tapered to very snugly receive said sliding staff, and means engaging and frictionally retaining said sliding staff in said bore, said frictional engaging means comprising an annular formed on the adjacent end of the balance staff and engageable in said recess.

5. A balance staff assembly for watches comprising, a balance staff; unitary balance wheel, roller table and hairspring assembly structures secured rigidly but removably in true assembly relation on said staff; said balance staff having an axial bore therethrough, a sliding staff removably mounted in said bore having a length for extending at each end beyond said balance staff and having a pivot formed on each extended end, said sliding staff being tapered and said bore being similarly tapered to very snugly receive said sliding staff, and means engaging and frictionally retaining said sliding staff in said bore, said frictional engaging means comprising an annular recess formed in said sliding staff adjacent one pivot thereof and an inwardly spun annulus formed on the adjacent end of the balance staff and engageable in said recess, and said sliding staff having a positioning bead thereon disposed at the end remote from its recessed end and abutting the adjacent end of the'balance staff.

6. A balance staff assembly for Watches comprising, a balance staff element; a balance wheel, a roller table and a hairspring assembly mounted on said staff element; said balance staff element having an axial bore therethrough, a sliding staff element removably mounted in said bore having a length for extending at each end beyond said balance staff and having a pivot formed on each extended end, and means engaging and frictionally retaining said sliding staff element in said bore, said last named means comprising a detent carried by one said element and a detent receiving recess carried by the other of said elements.

7. A balance staff assembly for Watches comprising, a balance staff; a balance wheel, a roller table and a hairspring assembly mounted on said staff; said balance staff having an axial bore therethrough, a sliding staff removably mounted in said bore having a length for extending at each end beyond said balance staff and having a pivot formed on each extended end, said sliding staff being tapered and said bore being similarly tapered to very snugly receive said sliding staff, and means engaging and frictionally retaining said sliding staff in said bore, said frictional engaging means comprising an annular recess formed in said sliding staff adjacent one pivot thereof and an inwardly spun annulus formed on the adjacent end of the balance staff and engageable in said recess, and said sliding staff having a positioning bead thereon disposed at the end remote from its recessed end and abutting the adjacent end of the balance staff.

WILLIAM L. BRENDLER. 

